class TwigNamespaceTest

class TwigNamespaceTest extends KernelTestBase {
  
  /**
   * Modules to enable.
   *
   * @var array
   */
  protected static $modules = [
    'twig_theme_test',
    'twig_namespace_a',
    'twig_namespace_b',
    'node',
  ];
  
  /**
   * @var \Drupal\Core\Template\TwigEnvironment
   */
  protected $twig;
  
  /**
   * {@inheritdoc}
   */
  protected function setUp() : void {
    parent::setUp();
    \Drupal::service('theme_installer')->install([
      'test_theme',
      'olivero',
    ]);
    $this->twig = \Drupal::service('twig');
  }
  
  /**
   * Checks to see if a value is a twig template.
   *
   * @internal
   */
  public function assertTwigTemplate($value, string $message = '') : void {
    $this->assertInstanceOf(TemplateWrapper::class, $value, $message);
  }
  
  /**
   * Tests template discovery using namespaces.
   */
  public function testTemplateDiscovery() {
    // Tests resolving namespaced templates in modules.
    $this->assertTwigTemplate($this->twig
      ->load('@node/node.html.twig'), 'Found node.html.twig in node module.');
    // Tests resolving namespaced templates in themes.
    $this->assertTwigTemplate($this->twig
      ->load('@olivero/layout/page.html.twig'), 'Found page.html.twig in Olivero theme.');
  }
  
  /**
   * Tests template extension and includes using namespaces.
   */
  public function testTwigNamespaces() {
    // Test twig @extends and @include in template files.
    $test = [
      '#theme' => 'twig_namespace_test',
    ];
    $this->setRawContent(\Drupal::service('renderer')->renderRoot($test));
    $this->assertText('This line is from twig_namespace_a/templates/test.html.twig');
    $this->assertText('This line is from twig_namespace_b/templates/test.html.twig');
  }

}